A nonaqueous electrolyte secondary battery having high electromotive force that comprises a nonaqueous electrolyte and utilizes oxidation and reduction of lithium has recently been used as one of new type high output and high energy density batteries.
In such nonaqueous electrolyte secondary batteries, a carbon material such as graphite, coke, and the like, capable of occluding and releasing lithium ion is commonly used. When high crystalline graphite is used, a nonaqueous electrolyte secondary battery having high energy density can be provided. Therefore, such graphite has recently been widely used.
It has been proposed that a vinylene carbonate derivative is added to the nonaqueous electrolyte in a nonaqueous electrolyte secondary battery comprising a graphite as the negative electrode active material to improve cycle characteristics (Japanese Patent Laid-open No. 8-45545).
It is believed that a vinylene carbonate derivative is reduced during the initial charge of the battery in which the graphite is used as the negative electrode active material to form a surface film on a surface of the negative electrode active material. The surface film prevents a side reaction, for example, decomposition of the nonaqueous electrolyte, and the like, to improve the cycle life of the battery.
However, there is a problem that the surface film formed on the surface of the negative electrode active material reduces output characteristics when the battery is discharged at high current.